In the case of NHL rookies, coaches may have an idea of what they're going to get based on what they've seen in training camp and exhibition games, but they don't know until at least 20 games have been played.

We're not there yet, but we've seen several rookies who have at least dropped a very strong hint that they have earned their roster spot and will make a key contribution to their teams this season.

8. C Mark Arcobello, Edmonton Oilers

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Notable numbers: Eight assists in eight games; plus-five rating.

Analysis: Mark Arcobello is the most unheralded player on this list by a wide margin. Prior to the start of this year's training camp with the Oilers, the 25-year-old Arcobello had played one NHL game in his career and had the look of a career minor leaguer.

However, Arcobello earned his spot on the Oilers with his consistency and nonstop motor. While he is not going to impress you with his size or physical gifts—Arcobello is 5'8" and 166 pounds—he is not afraid to go into the dirty areas of the ice, and he is going to play as hard on the defensive end of the ice as he is in the attack zone.

Arcobello has not scored a goal yet, but his eight assists show that he's been in the middle of head coach Dallas Eakins' offense. The most eye-opening number is his plus-five rating for a team that has allowed 35 goals and has a minus-12 goal differential.

Arcobello may not be able to hang with the prime Rookie of the Year candidates throughout the season, but he appears to be the kind of player who will help the Oilers and figures prominently this season.

7. RW Alex Chiasson, Dallas Stars

Notable numbers: Three goals, three assists in eight games; 23 shots on goal

Analysis: Alex Chiasson was a second-round pick of the Stars in 2009, and he has worked his way up through the minor leagues to earn his spot on the roster this year.

Head coach Lindy Ruff looks at Chiasson, 23, and likes his size—6'3" and 202 pounds—and the way he attacks the net. Chiasson has the instincts to know exactly where to go to get scoring chances, and it's a gift that Chiasson has that many veteran players do not.

"He's one of those guys that just knows how to get it done," Ruff told Steve Hunt of NHL.com. "If you could coach it we'd probably have 12 guys on every team that would be scoring like that. But he's got that great natural gift around the net."

6. C Sean Monahan, Calgary Flames

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Notable numbers: Four goals, two assists in six games; 30.8 shooting percentage.

Analysis: Sean Monahan, 19, is in an ideal situation for a young player. His job is simply to develop his skills at the NHL level. Since he is playing for a team that is going through the rebuilding process, there is very little pressure.

The Flames have gotten off to a stellar start, but they are not a playoff team in the tough, deep Western Conference. Monahan is an intelligent player with excellent hockey instincts. He understands where to go and has the skills to set up his teammates and take advantage of his own opportunities.

If Monahan continues to play at this level, he will soon become a player who is the focus of the opponent's defensive game plan. It may be much more difficult to produce under those circumstances, but it is clear that he belongs with the Flames this season.

5. C Aleksander Barkov, Florida Panthers

Notable numbers: Two goals, three assists in eight games; one power-play goal.

Analysis: Aleksander Barkov, 18, is one of the key players that Florida Panthers general manager Dale Tallon is trying to build his team around.

Barkov was the second overall pick in last year's draft, and he is the full package at 6'2", 209 pounds. Barkov is a brilliant skater who also plays a heavy game. He is not afraid to bang with the bigger bodies in the league, and he has a scorer's instinct.

Barkov will go to the net and establish position and battle to get tips and rebounds. He also has the speed to fly around the defense and get open. Head coach Kevin Dineen told the Miami Herald that he has been impressed with Barkov's development and that his talented young player looks like he belongs in the NHL.

4. D Torey Krug, Boston Bruins

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Notable numbers: One goal, two assists in six games; plus-two rating; 17:37 ice time per game.

Analysis: Torey Krug established himself as an important player for the Boston Bruins in last year's playoffs when he scored four goals in a five-game triumph over the New York Rangers in the conference semifinal.

It seemed that Krug's future with the Bruins was sealed with that impressive performance, but Krug had to go to training camp and win his position because the Bruins are so deep along the blue line. Still, Krug is an excellent puck-moving defenseman who has exceptional athletic skills. He can kick the puck from his skate to his stick, and that allows him to get a shot or a pass off in an instant.

Krug, 22, looks undersized at 5'9" and 180 pounds, but he can win the battle in the corner and come away with the puck. His ability to turn defense into offense provides head coach Claude Julien with an important element that the team would not have without him.

3. C Nathan MacKinnon, Colorado Avalanche

Analysis: Nathan MacKinnon, 18, was a surprising No. 1 pick for the Avalanche last summer. MacKinnon had established himself as the best offensive player in the draft, but the Avs were so deficient on the blue line that it seemed like they would go after defenseman Seth Jones with the No. 1 pick.

Through the very early going, general manager Joe Sakic has no regrets about the pick. MacKinnon has played like a skilled, intelligent center with eye-catching physical gifts through his first seven games. MacKinnon is one of the fastest players in the league and has used that speed to slice through opponents and set up scoring opportunities.

The Avs have gotten off to a surprising 6-1-0 start under rookie head coach Patrick Roy. They may not be able to keep up this pace, but it's clear that MacKinnon is going to play a key role with the team throughout the season and for years to come.

2. D Seth Jones, Nashville Predators

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Notable numbers: One goal, two assists in seven games; 23:46 of ice time per game

Analysis: After being touted as a top prospect throughout much of the 2012-13 season with the Western Hockey League's Portland WinterHawks, Seth Jones, 19, may have been bothered because he slipped to the No. 4 pick in the draft, but he never showed it.

Instead, Jones has kept his mind on his business from the first day of training camp and has looked like an NHL defenseman every step of the way. Jones, at 6'4" and 205 pounds, has the size to dominate the game as he develops. While he needs to get stronger, he can handle himself in the corners and knows what to do in all situations.

Jones has earned head coach Barry Trotz's confidence, as he is playing heavy minutes early in his rookie season.

"There's still a lot for [Jones] to understand, the nuances of the pro game, but his hockey sense and ability have allowed him to maybe fend off some of those extreme nuances," Trotz told Harvey Fialkov of the Fort Lauderdale Sun-Sentinel. "I can see him being very dominant for a long time.''

1. Tomas Hertl, San Jose Sharks

Analysis: The classic formula for rookie success is for the young player to burst onto the scene with a stellar performance that makes the hockey world take notice. Then, once he has the spotlight on him, he continues to build on that showing with consistent excellence.

Tomas Hertl, 19, certainly had the first part of it down without a hitch. Hertl had a remarkable four-goal outburst in a 9-2 San Jose victory over the New York Rangers Oct. 8. The final goal in that game was an artistic between-the-legs shot that went up and over New York goalie Martin Biron and into the top corner of the net.

Hertl has creativity, speed and is an opportunistic scorer. He also is part of the young phalanx of players who have taken the leadership baton on the Sharks. As long as Hertl stays healthy, he will play a key role for the Sharks this season and for many future years as well.